diff --git a/contrib/tablefunc/expected/tablefunc.out b/contrib/tablefunc/expected/tablefunc.out
index 06d8b41e603ea3621c5d2552a4104da8615b67ef..9b04bfa4f5c06fa3dc86be994c1346de284a01fd 100644
--- a/contrib/tablefunc/expected/tablefunc.out
+++ b/contrib/tablefunc/expected/tablefunc.out
@@ -177,3 +177,41 @@ SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0) AS t(k
9 | 5 | 2
(6 rows)
+-- recursion detection
+INSERT INTO connectby_int VALUES(10,9);
+INSERT INTO connectby_int VALUES(11,10);
+INSERT INTO connectby_int VALUES(9,11);
+-- should fail due to infinite recursion
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') AS t(keyid int, parent_keyid int, level int, branch text);
+ERROR: infinite recursion detected
+-- infinite recursion failure avoided by depth limit
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 4, '~') AS t(keyid int, parent_keyid int, level int, branch text);
+ keyid | parent_keyid | level | branch
+-------+--------------+-------+-------------
+ 2 | | 0 | 2
+ 4 | 2 | 1 | 2~4
+ 6 | 4 | 2 | 2~4~6
+ 8 | 6 | 3 | 2~4~6~8
+ 5 | 2 | 1 | 2~5
+ 9 | 5 | 2 | 2~5~9
+ 10 | 9 | 3 | 2~5~9~10
+ 11 | 10 | 4 | 2~5~9~10~11
+(8 rows)
+
+-- test for falsely detected recursion
+DROP TABLE connectby_int;
+CREATE TABLE connectby_int(keyid int, parent_keyid int);
+INSERT INTO connectby_int VALUES(11,NULL);
+INSERT INTO connectby_int VALUES(10,11);
+INSERT INTO connectby_int VALUES(111,11);
+INSERT INTO connectby_int VALUES(1,111);
+-- this should not fail due to recursion detection
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '11', 0, '-') AS t(keyid int, parent_keyid int, level int, branch text);
+ keyid | parent_keyid | level | branch
+-------+--------------+-------+----------
+ 11 | | 0 | 11
+ 10 | 11 | 1 | 11-10
+ 111 | 11 | 1 | 11-111
+ 1 | 111 | 2 | 11-111-1
+(4 rows)
+
diff --git a/contrib/tablefunc/sql/tablefunc.sql b/contrib/tablefunc/sql/tablefunc.sql
index 25b430e4a03cd7e49d26e168f7daf5dd4759bae7..a450670d50812476fe3d10a47af17e2c5cb857d2 100644
--- a/contrib/tablefunc/sql/tablefunc.sql
+++ b/contrib/tablefunc/sql/tablefunc.sql
@@ -58,3 +58,24 @@ SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') A
-- without branch
SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0) AS t(keyid int, parent_keyid int, level int);
+-- recursion detection
+INSERT INTO connectby_int VALUES(10,9);
+INSERT INTO connectby_int VALUES(11,10);
+INSERT INTO connectby_int VALUES(9,11);
+
+-- should fail due to infinite recursion
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 0, '~') AS t(keyid int, parent_keyid int, level int, branch text);
+
+-- infinite recursion failure avoided by depth limit
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '2', 4, '~') AS t(keyid int, parent_keyid int, level int, branch text);
+
+-- test for falsely detected recursion
+DROP TABLE connectby_int;
+CREATE TABLE connectby_int(keyid int, parent_keyid int);
+INSERT INTO connectby_int VALUES(11,NULL);
+INSERT INTO connectby_int VALUES(10,11);
+INSERT INTO connectby_int VALUES(111,11);
+INSERT INTO connectby_int VALUES(1,111);
+-- this should not fail due to recursion detection
+SELECT * FROM connectby('connectby_int', 'keyid', 'parent_keyid', '11', 0, '-') AS t(keyid int, parent_keyid int, level int, branch text);
+